Added methods and events for subnode, subview and layout add/remove.

Added constantlayout.
Added variablelayout.
Added shrinktofit.
Added alignlayout.
Added spacedlayout.
Added wrappinglayout.
Added resizelayout.

Fixed a few big issues that came up once I started adding/removing views after initialization. There is/was a problem with the scope for event binding which I worked around. Moved the subnodeAdded events to a time after all but the late attrs have been set so that wierd race issues will not occur.